See a new photo of Kristen Stewart stripping down to her bra and underwear to go skinny dipping on the set of Sils Maria in Switzerland.Credit: RAMEY PHOTO

Ciao Bella! Kristen Stewart stripped down to her underwear on the set of Sils Maria on Sept. 23 in Switzerland. The 23-year-old Twilight actress was photographed filming a skinny dipping scene with costar Juliette Binoche.

Stewart, sporting a tattoo below her right elbow for the role, wore a black bra and white boy shorts underwear for the scene, while Binoche, 49, appeared to go completely nude. The two ladies were seen smiling as they went swimming in a lake.

Sils Maria tells the story of an aging actress (Binoche), who stars in a revival of a play that made her famous, but opposite the young role (played byChloe Grace Moretz) she once had. Stewart will play a supporting part as Binoche's assistant in the Olivier Assayas-directed film.

"It takes two very particular people to have that relationship be functional -- one that services the other -- because Juliette Binoche is playing the actress that I assist, and she is one of the most powerful women I think I've ever seen in film," Stewart told WWD in July. "I'm going to try desperately to not be squashed by a woman like that, and it's not going to be an easy thing."

Bionche starred opposite Stewart's ex-boyfriend, Robert Pattinson, in the 2012 film Cosmopolis. Stewart and her Twilight costar ended their longtime romance back in May. Since then, the 27-year-old actor hooked up with Elvis Presley's granddaughter Riley Keough over the summer, and a source told Us Weekly he's currently dating Sean Penn's daughter Dylan Penn. "They've been together a few months and they're very comfortable," a source told Us. "He's so happy now." Stewart, meanwhile, is currently not dating anyone. "She's just been focusing on filming," an insider told Us.